This has probably been asked and answered many times but--I tow a vehicle 4 down and get 7-7.3 MPG regardless if 55 MPH or 65 MPH. My GCVW is around 18000#. Wondered if anyone towing a lighter vehicle ( around 3500#) might get better mileage? I know it is a big box but at $3.70 per gallon--wheww!
thanks

We towed 7000 miles last summer ON to BC and Oregon and rtn. Averaged 8 - 8.5 mpg, towing a Honda Accord. Later took a 500 mile trip without the towed and no mountains, and deliberately kept to a maximum speed of 55, averaged 7.5mpg.

Thanks for the input. I have a 2001 31c and tow a Ford 4x4 Explorer.
Scatch my head on the answer from Beverley&Ken. jbbrick sounds about like mine, but a I am a little lighter. Wonder if my 4x4 even with tranaxle in neutral is the drag!! thinking about getting a Jeep Wrngler, but may not make that much difference. :-(

We use a tow dolly pulling a 2004 Volkswagen New Beetle.2005 Four Winds 31' E450 Ford chassis with the Triton V10.
We did a run to Maine last year and we averaged around 8 and 8.5.We stayed around 55-60mph
We just got back from South Dakota/Wyoming trip last month and we averaged 7.5 and 7 with the cab air running.One difference this time is that our speed was faster,we tried staying at 65-70mph.
I have to say Nebraska killed our MPG,we dropped to around 6 and sometimes to 5.5.The wind was just in our face across the whole state and wow what a long state to get across!

Basically been all over US the last 6 years with the Winnie C.--- West, NW, NE, East and SE. Looks like I was right in that a lighter vehicle would only make a slight difference in overall mileage. I know "big foot", wind, hills, mtns each makes a big difference. My 2001 V-10 is only the 2 vlv engine, I think, and i am sure the later model V-10's do perform better. Thanks to all for your input. :-)